Air-conditioning: Hot Facts about Cooling

Did you know that aerodynamics experts are involved in air-conditioning design? And that ŠKODA has a climate chamber that can recreate the conditions you’d find in Arizona? Development experts let us in on some interesting facts about the ventilation system.

13. 6. 2019 Škoda World Innovation & technology Technology

The ventilation set-up is a complicated system that is being continuously honed. And not all air-conditioning is the same. The latest Climatronic system can surprise even seasoned motorists by delivering the unexpected, such as detecting airborne pollutants and automatically shutting off the outside air inlet. No wonder: every innovation is the result of thousands of hours of development and testing in normal traffic situations.

State-of-the-art techniques and computer simulations are also applied in the design of a ventilation system. One of the reasons for this is that the air-conditioning in a ŠKODA must provide comfort to all shapes and sizes – square-shouldered men, slim women, gangly youths and diminutive seniors – in all sorts of climate zones from the north of Europe to distant China.

“For our purposes, we usually set the temperature inside the chamber to 40 degrees,” explains air-conditioning development coordinator Jan Hrnčíř. “Air-conditioning efficiency is verified using standardised pull-down testing. We can set up the fluorescent lamps to simulate a burning sun at 1,000 W per m², which is consistent with conditions you might find in the Arizona desert. We monitor passenger comfort with the aim of reaching a temperature of around 25 °C at passenger head level within 20 minutes.”

To make everything work truly automatically, with no need for driver corrections, whether in the temperate climate of the Czech Republic or in scorching Australia, a lot of precise calculations, plenty of experience, and patient testing are essential. The individual ŠKODA models feature the same air-conditioning system regardless of the market. Only the software is region-specific.

Even the interior has aerodynamics

The Aerodynamics Development Department and its specialists focusing exclusively on internal aerodynamics also make significant contributions to the design of new air-conditioning. Most people have probably seen images from tests where streamlines flow around a car body more or less in an orderly fashion. What they may not know is that ever-increasing attention is being paid to internal aerodynamics. Here, the airflow in the cabin is monitored as it not only affects passenger comfort, but also, perhaps surprisingly, safety and acoustics.

“Proper airflow ensures good visibility from the car, defrosts the windows in winter and prevents fogging throughout the year,” explains internal aerodynamics coordinator David Svítil. Computers also help to detect whether airflow will cause an unpleasant whizzing sound. Calculations can improve the design and reduce the development time and the cost of tests. What once took experts months can now be handled in days.

“When a new car is being designed, we work with the Design Department on the distribution of the ventilation system’s various components,” says David Svítil. “For example, the SCALA and the KAMIQ have high-mounted on-board infotainment screens, so the blowers in the middle of the dashboard had to be lowered. Using computer simulations, we could instantly shape and design them to make the airflow in the cabin as comfortable as possible,” explains the aerodynamics expert.

In the virtual cabin of a future car, the main factors monitored are the direction and velocity of the air, taking into account the amount of air supplied and the acoustics. “It’s not just the fans that can be a source of noise. Air may also be heard as it passes through narrow slots,” notes David Svítil.

The whole system design, including the shape of the distribution components and vents, is adapted to this. The calculations are then verified with tests in the climate chamber and on ordinary roads. Not even the very best climate chamber can replace practical tests.

“The chamber will show us the overall performance and efficiency of the ventilation system, but it can’t simulate the software set-up conditions. This is something we have to examine over thousands of kilometres on cold mornings, hot days and in alternating and rainy weather,” adds Jan Hrnčíř.

First the air-conditioning, then a prototype

In practice, a new ventilation system is tested even before the first prototype is made. These tests are carried out using cars which, from the outside, are virtually indistinguishable from a production car, but inside conceal the technology that is being developed.

“We drive in polar regions and in the desert. Obviously, these are extremes,” says Jan Hrnčíř. “Spring and autumn alpine environments are ideal testing grounds for the automatic mode. You may be in a situation where it’s frosty outside, but the harsh rays of the sun are warming the interior. That’s the most complicated situation for the control system to handle. Using a range of sensors, the ventilation system must correctly adjust the flow rate and temperature for both the feet and the head so that the car’s occupants feel comfortable and don’t need to adjust the settings.”

Comfort first

Air-conditioning ceased to be a luxury long ago. For example, when it comes to ŠKODA, all FABIAs feature air-conditioning as standard, and the new SCALA hatchback’s Style trim level incorporates Climatronic automatic dual-zone air-conditioning.

In higher-end models, such as the KODIAQ and SUPERB, you’ll even get three-zone Climatronic, with separate backseat passenger controls. This is not a superfluous luxury, as anyone who has experienced disagreements about the interior temperature on the way to the sea for their summer holiday will testify. Three-zone climate control helps to keep parents from being soaked in sweat under the large windscreen without making the kids in the back sneeze with cold.

Modern automatic air-conditioning also switches the internal recirculation on and off automatically in response to air pollution. Few know that Climatronic is in recirculation mode most of the time. ŠKODAs such as the OCTAVIA and KAROQ offer Air Care, a function that automatically prevents contaminated air in conurbations or dusty environments from entering the car. A secondary advantage is the cabin air re-filtering, because the air passes through a cabin filter even when recirculation mode is on. The humidity sensor stops any sudden misting of the glass. The system also bears in mind the need to ventilate with fresh air so that the occupants do not find themselves in a stuffy environment for too long. It mixes outdoor and indoor air as and when conditions allow.

In modern automatic air-conditioning, there are many more sensors at work. They monitor outside and inside temperature and humidity, system pressure, and the compressor settings. The sunlight sensor is also important as it can detect not only the intensity, but also the direction, of the sun’s rays. It adjusts the air temperature for the left and right side of the car accordingly. Automatic climate control is much more beneficial to users than it seems.

New opportunities with electric cars

Another reason why ŠKODA’s ventilation system design and testing facilities are of such a high standard is that, as of 2019, ŠKODA no longer uses the Group’s assembled units. Under the INDIE 2.0 project, it is developing a modified platform that not only includes the chassis and powertrain, but also the ventilation system. This places new demands on the Development Department. “From a designer’s point of view, with development there is a difference between adapting a ready-made part and developing something entirely new,” emphasises Jan Hrnčíř.

Another major change is the development of electric cars. So far, ventilation has been a marginal energy management issue, since it has used the engine’s waste heat for heating and has essentially supplied cooling via air-conditioning in the summer. With the advent of electrically-propelled vehicles, the ventilation system has become one of the most important electrical appliances in the vehicle. This places all the more pressure on the efficiency of heating and cooling.

Cooled before you set off

Development is of great importance, and new opportunities are being thrown up by this paradigm shift. As an electric car obviates the need for the engine to be running in order to start the air-conditioning, future electric vehicle users can look forward to a well-tempered interior as soon as they get in. The ideal situation would be to cool the interior while the car is connected to the charging point.

In electric cars, designers will pay a lot more attention to the acoustics. So far, the main noise in the cabin has come from the engine and the aerodynamics. In exceptionally quiet electric vehicles, details such as the murmur of the airflow and the humming of the fan will come to the fore. “Computer models are a big help to us because they find out exactly where unwanted swirls might occur. Armed with this knowledge, we can overhaul the design of the air vents,” says Jan Hrnčíř. This is precisely what the Development Department is working on now. We will see the first results in the ŠKODA VISION iV in 2020.